Ink system for printing machines

ABSTRACT

An ink system is provided wherein ink is pumped from a container to an enclosed ink fountain, thereby eliminating exposure of the ink to the atmosphere. A flexible diaphragm constitutes a cover for the ink fountain. In its retracted and distended positions the diaphragm, by electrical means, controls the starting and stopping of the pump to assure an adequate supply of ink in the fountain and automatic replenishing of the ink used.

United States Patent [72] Inventors AlbertE.Mignone Shaker Heights; Donald J. Miller, Lakewood; Raymond J. Schmidlin, Lydhurst, all of Ohio [21] Appl. No. 748,709

[22] Filed July 30, 1968 [45] Patented Jan. 4, 1972 [73] Assignee Addressograph Multigraph Corporation Cleveland, Ohio [54] INK SYSTEM FOR PRINTING MACHINES 8 Claims, 4 Drawing Figs.

[52] US. Cl 101/350, 101/366, 222/64, 137/386 [51] Int. Cl B41t31/06 [50] Field ofSearch 101/366,

[5 6] References Cited UNITED STATES PATENTS 477,422 6/1892 Kellom 101/366 5/ 1 946 Metzner et a1 6/1959 Maki 3,025,793 3/ 1 962 Vischulis. 101/350 3,316,926 5/1967 Worth 137/102 3,318,238 5/1967 G0ttsch0.... 101/364 X 3,342,376 9/1967 Smith 222/64 3,354,823 11/1967 Lake 101/366 X 3,470,905 10/1969 Heskett 137/571 3,453,138 7/1969 Chen etal 101/363 X 3,029,324 4/1962 Couffer, Jr. et al. 137/102 X FOREIGN PATENTS 954,510 4/1964 Great Britain 101/366 626,707 7/1949 Great Britain 101/364 Primary Examiner-J. Reed Fisher Att0rneysRussell L. Root, Ray S. Pyle and Wilmer H. Nau

ABSTRACT: An ink system is provided wherein ink is pumped from a container to an enclosed ink fountain, thereby eliminating exposure of the ink to the atmosphere. A flexible diaphragm constitutes a cover for the ink fountain. In its retracted and distended positions the diaphragm, by electrical means, controls the starting and stopping of the pump to assure an adequate supply of ink in the fountain and automatic replenishing of the ink used.

INK SYSTEM FOR PRINTING MACHINES This invention relates to printing machines and, more particularly, to an ink system for use in printing machines.

Conventional ink systems usually comprise a fountain which contains the ink, and a roller which rotates in the fountain, picking up ink and feeding it to additional rollers and eventually to the printing form which may be in the nature of a planographic plate or master, or raised-type characters. Generally, the ink fountain also includes an adjustable doctor blade which is spaced from the fountain roller a predetermined distance so as to control the amount of ink picked up by the roller.

Such ink systems have been in use for many years and perform satisfactorily to the extent of their limitations. For example, one disadvantage has been the fact that the ink fountain is exposed to the atmosphere and becomes a target for foreign matter such as dust, dirt, paper lint, and the like, all of which may be fed with the ink onto the finished printed copy, thereby adversely affecting the quality of the print. In addition, ink laying in an exposed ink fountain for too long a time tends to have a skin formed thereon. To avoid this condition, it is necessary to clean the fountain of aging ink at frequent intervals, a time-consuming chore.

Another disadvantage of conventional ink systems is that the ink supply in the fountain must be replenished from time to time in the course of normal operation of the printing machine and the usual practice is for the operator to perform this duty manually with the aid of a spatula, putty knife, or the like, being careful to apply the ink uniformly along the fountain roller and to avoid getting any of the ink on other parts of the machine and thus creating an untidy operating condition.

The present invention has as its primary object the provision of an ink system which can be permitted to stand for long intervals between uses without ink deterioration, and in which the ink is continually protected from contamination by foreign matter or foreign by air contact.

This object is achieved according to the present invention by providing an enclosed ink supply system for a printing machine in which the ink remains completely concealed and unexposed to the atmosphere, and thus free from possible oxidation, from the time it is housed in the original container until it is transferred from the ink fountain roller to other rollers in the ink train.

Another object of the invention is to provide for automatic replenishment of the ink in the ink fountain to thereby insure an adequate working level of ink in the fountain regardless of the amount being used in the printing operation, and, at the same time, avoid the disadvantages and messiness generally associated with manually adding ink to the ink fountain, and to simplify the introduction of a new ink supply when necessary. Other and further objects, features and advantages of the present invention will be apparent as the description proceeds.

IN THE DRAWINGS:

FIG. I is a front elevation of a printing machine having an ink supply system embodying the features of the present invention;

FIG. 2 is a plan of an ink fountain incorporated in the printing machine illustrated in FIG, 1;

FIG. 3 is a section, on an enlarged scale, taken on the line 3-3 of FIG. 2; and

FIG. 4 is an exploded elevational detail on an enlarged scale, showing an ink container utilized in the ink supply system, with a portion of the container broken away, and showing the same in relation to a pump inlet.

In FIG. 1 there is shown a printing or duplicating machine, indicated generally by the reference numeral 10, in which the inking system of the present invention may be utilized. It should be understood, however, that the concept described and claimed herein may be applied to a variety of printing and duplicating machines and, in fact, to any apparatus where the use and automatic feeding of inklike materials is desired.

The printing machine has mounted thereon an ink unit, indicated generally at 12, which includes one or more ink transfer rollers such as, for example, rollers 14, I6 and 18,

which are effective to transfer ink from an ink fountain roller 20 to a printing plate or form (not shown). As shown in FIG. 3, fountain roller 20 is rotatably mounted in an ink fountain 22.

Ink fountain 22 may be of one-piece construction, e.g., a casting, or it may be an assembly of individual parts. It is deemed sufficient for an understanding of the invention to merely state that, as shown in FIGS. 2 and 3, fountain 22 comprises a pair of sidewalls 24a and 24b, a front wall 26a, a rear wall 26b and an ink chamber C. As shown in FIG. 3, the rear wall 26b may conveniently be extended so as to provide a base 28 for ink fountain 22. To prevent leakage of ink from fountain 22, wiper pads 29, FIG. 2, are provided at each end of fountain roller 20, i.e. between the ends of the fountain roller and sidewalls 24a and 24b of fountain 22. Wiper pads 29 preferably should be of a porous, resilient material such as, for example, felt.

In a preferred form of the invention, as seen in FIG. 3, fountain 22 is depicted as having a pair of openings, shown by the reference numerals 21 and 23. Opening 21 accommodates fountain roller 20. The purpose of the other opening 23 will become apparent as the description proceeds.

The thickness of the film of ink picked up by the fountain roller 20 is controlled by means of a doctor blade 30 which may be mounted, by way of example, on an inclined portion 260 or rear wall 26b, as shown in FIG. 3, and retained by screws 32 threadingly engaging a backup plate 34. A series of spaced-apart thumbscrews 36, FIGS. 2 and 3, are provided to enable the operator to position doctor blade 30 toward or away from fountain roller 20 to thereby regulate the amount of ink picked up by fountain roller 20.

In FIG. 4 there is shown a preferred form of ink source comprising an ink container 40 having at one end a complementary cover 42 of the screw-on type. The other end of container 40 is provided with a neck 44 which serves as a spout. The neck 44 includes as an integral portion thereof a closed tip 440. For the purpose of the description which will follow concerning the functional advantages of the ink source, the parts thereof, referred to immediately hereinabove, are shown in FIG. 4 as having been separated. It is to be understood that for purposes of shipping, storage, etc., or at a time prior to use in the printing machine, cover 42 is fastened to container 40 and tip 44a is an integral portion of neck 44 of container 40. The container 40 is made of a suitable semirigid plastic material so that the tip 44a can be readily removed bycutting with a knife. To this end a line of weakening is preferably appropriately located about the neck 44 to assist in this operation.

Under certain conditions, as will be explained more fully hereinafter, it may be advantageous to employ a follower F to cause the ink to be withdrawn from container 40 in a uniform manner.

With reference to FIG. 1, a pump P, driven intermittently by a motor M and connecting belt 45, is provided as a source of power means for the purpose of feeding ink from container 40 to ink fountain 22 through an interconnecting tube or passageway 46. Pump P may be a conventional screw-type pump since a pump of this nature has been found to perform satisfactorily.

An inlet 48 is provided on pump P to receive ink from the ink source or, more specifically, from container 40 by way of neck or spout 44. As shown in detail in FIG. 4, neck 44 is designed to fit snugly in an opening 480 of pump inlet 48.

Referring again to FIG. 1, pump P is provided with an outlet 50 through which the ink is conveyed through a hollow coupling 52 and into passageway 46. For operator convenience, coupling 52 may include a gauge 54 which affords a ready checkpoint to indicate malfunction of the pump or the motor, or depletion of the ink supply, or the like. Coupling 52 may also include a conventional petcock 56 which is useful in checking the flow of ink, draining of the pump, etc. Passageway 46 terminates in an inlet 58, FIGS. 2 and 3, through which the ink reaches ink fountain 22.

As stated hereinabove, ink fountain 22 has a pair of openings, 21 and 23, opening 21 accommodating fountain roller 20. With reference to FIGS. 2 and 3, within and closing the opening 23 there is positioned a flexible diaphragm 60. Diaphragm 60 is preferably of such dimension, as to constitute a cover for ink fountain'22, thereby protecting the surface of the ink in the fountain against contamination by foreign matter and oxidation byrair contact. Thus, it will be readily seen that positioning of diaphragm 60 in opening 23, and placement of ink fountain roller in opening 21, affords a substantially closed structure for ink fountain 22.

Diaphragm 60 may be ofany suitable, thin flexible material which is not subject to deterioration due to contact with the ink in chamber C. It has, been found that a plastic material, such as polyethylene, for example, performs entirely satisfactory for this purpose.

Diaphragm 60 is assembled to ink fountain 22 in a somewhat loose or slack manner, i.e. not taut, so that it may assume what might be termed two positions, e.g., an outer or distended position, as indicated by full lines in FIG. 3, and an inner or retracted position as indicated by broken lines. Diaphragm 60 is mounted between a pair of frame members 62 and 64 and may be fastened thereto, for example, by screws 66 threadingly engaging frame 64. To prevent possible leakage of ink at this point, a gasket 68 of substantially the same dimensions as lower frame member 62 may be placed between diaphragm 60, and one of the frame members 62 or 64. For ease and convenience of retaining diaphragm 60 on ink fountain 22, upper frame member 64, as viewed in FIGS. 2 and 3, may include angular portions 64a which are fastened to ink fountain 22, for example, by screws 70.

As shown in FIGS. 2 and 3, a sensing plate 72 is in surface contact with an exposed portion of diaphragm 60 and is movable therewith. Sensing plate 72 may be formed so as to include ears 74 which are perforated to permit the sensing plate to be pivotally mounted on a pin 76 which in turn is held by a bracket 78 mounted on ink fountain 22.

Riding on sensing plate 72 is a sensing finger 80 of a control switch 82. Switch-82 is connected by an electric circuit 84 to motor M which is energized when the sensing finger 80 is in approximately the broken line position shown in FIG. 3.

Sensing plate 72 is shown in FIG. 2 as being of such size that it contacts, or rests on, only a small portion of the exposed surface of diaphragm 60. Such illustration is by way of example only, since it is recognized that under certain conditions, e.g. when a low-viscosity ink is employed, it may be desirable to have more extensive surface contact between the sensing plate 72 and the exposed portion of diaphragm 60. With a small area of contact and low-viscosity ink it has been found that, even with very light spring loading of the arm 80, it is possible for the latter to depress the diaphragm locally so as to give erroneous or erratic level indications. With greater surface contact, there is less likelihood of the plate 72 depressing only a local portion of the surface of the diaphragm while the general level remains higher, and the resulting tendency to overfill the fountain with consequent chance for ink leakage at the diaphragm connections is avoided. It follows that when an extremely high-viscosity ink is employed, even sensing plate 72 may be dispensed with, and sensing finger 80 may be arranged to make direct contact with diaphragm 60. The viscosity of the ink employed is controlling in this respect, and the contact area is so adjusted that the sensing finger 80 will move reliably in unison with the general level of diaphragm 60. It is, therefore, considered within thepurview of the invention that if a member such as sensing plate 72 is utilized, it should be of a surface dimension which, considering the degree of loading applied by the sensing means, is capable of reliably following the breathingmotion of the diaphragm 60 which, as shown in FIG. 3, is between the distended position shown in solid lines and the retracted position shown in broken lines.

It is also considered within the scope of the invention that sensing plate 72, if included, may be a part of, oraffixed to, sensing finger 80 rather than as shown in FIGS. 2 and 3.

Also shown in FIG. 3 is a strip. 86 of flexiblematerialwhich may be fastened to the inside of frontwall 26a of ink fountain 22 in the manner shown. Strip 86 extends over a portion of the periphery of ink fountain roller 20, thus bridging the clearance gap between the lower edge of wall -26a of ink fountain22 and roller 20. Strip 86 preferably is of a length at least equal to the length of ink fountain roller20, thereby providing a seal to prevent possible leakage of ink, particularlyink of low viscosity, at this point, and thus further insuring a closed ink fountain structure. Since sealing strip, 8 6 is flexible, it permits free rotation of ink fountain roller 20 even in an instance when foreign matter may be backed onto the fountain rollerfrom the other ink rollers, l4, l6, l8, Suchan incident causes temporary flexing of sealing strip 86 to the broken. line position shown..The direction of slope of the strip is,.however, such that thepressure of the ink, which is maintained at av height substantially above the level of the strip, tendsto tighten the grip onthe roller and insure sealing action. Material such as, for example, polyethylene terephthalate, sold under the trademark Mylar, has been found to function satisfactorily for the strip 86 due to its flexibility and toughness, and its quality of being resistant to chemical reaction with inks.

To summarize the operation of the ink system described in detail hereinabove, it is deemed advisable first to assume, that the ink system is devoid of ink, as would occur in the case of a newly installed printing machine, a change in ink colors, etc. Starting in this manner, tip 44a is I severed or otherwise removed from neck 44 of container 40 and the container is inverted to the position shown in FIG. 4. Neck44 is inserted into opening 48a of pump inlet 48 with a snug friction fit. Cover 42 may be removed from container 40, although it has been found that merely loosening-the cover is sufficient to relieve any vacuum and permit the ink to be withdrawn from the container and, at the same time, prevent foreign matter from falling into the ink.

At this point, it should be mentioned that since chamber C of ink fountain 22 contains no ink, diaphragm, 60, sensing plate 72 and sensing finger-.80 are in theretracted or broken line positions shown in FIG. 3.

Motor M is switched on to actuate pump P, thereby drawing ink from container 40. As the pumping action continues, ink is fed through passageway, and inlet 58, into ink chamber C of ink fountain 22. As the level of ink pumped into chamber C rises due to the continued running of pump P, it reaches diaphragm 60 which, it mustbe remembered is in the broken like position shown in FIG. 3, and gradually forces it upwardly. Sensing plate 72 which is resting on diaphragm,60, and sensing finger which is resting on sensing plate 72, naturally follow the upward, or outer movement of diaphragm 60. Such movement continues ,until diaphragm ,60, sensing plate 72 and sensing finger 80 reach the distended full line positions shown in FIG. 3. At this point, ink chamber C is filled with ink and a important aspect of the arrangement disclosed is realized, i.e., sensing finger 80 reaches its oft position, thereby opening switch 82 v and discontinuing power through circuit 84, shutting off motor M, With the stopping of the motor, the action of pump P is arrested, thus, discontinuing supplying of ink to ink fountain 22.

Mention has been made of the objective of providingink closed ink fountain. This feature should not be confusedwith what might be termed an airtight" fountain. An airtight fountain is neither necessary nor desirable to practicethe novel aspectsdisclosed herein due to theinherent problems created thereby, not the least of which would be considerable additional cost. For example, if ink fountain 22 were tightlysealed against escape of air, some means would be required to exhaust the air from the fountain followingthe start of the flow of ink through passageway 46. If this were not done, air would be pushed into fountain 22 ahead of the ink causing premature flexing of diaphragm 60 to its distended position, with the result that pump P would be shut off prior tocompletefilling of the fountain.

The above-mentioned condition is avoided, at least until such time as the ink reaches a level approximately equal to the position of ink-sealing strip 86, FIG. 3, by felt wiper pads 29 which because of their resiliency permit ink fountain roller to rotate and, because of their porous nature also serve to permit escape of air between the ends of roller 20 and sidewalls 24a and 24b of fountain 22.

Assuming that ink has been pumped into fountain 22 and has reached the level of ink sealing strip 86, the aforesaid provision for air escapement is, of course, no longer effective. However, this factor was considered in the design of the diaphragm-retaining means and it will be noted that frame members 62 and 64, diaphragm 60 and gasket 68 are assembled in a manner so as to be positively held together by screws 66 but that the spacing between the screws is such that air may be permitted to escape without leakage of ink, even ink of low viscosity. When the fountain is full, all these minute air leakage passages are sealed off by the ink so that virtually no oxygen is allowed to come in contact with the ink anywhere within the ink system.

It should be understood that operation of the printing machine, i.e., the running of copies therefrom, need not wait until ink chamber C is completely filled. The printing operation may be started when the ink in the chamber is at a level SUfiICiCl'IT. to provide a film of ink on the periphery of ink fountain roller 20 as the roller is normally rotated.

During the time the printing machine is operating and ink is being consumed in the printing of copies, the supply of ink in chamber C, of course, gradually decreases to the point where replenishment is desirable. Unlike conventional ink systems wherein adding ink to the fountain is effected manually, the novel arrangement disclosed provides automatic replenishment of the ink. For example, diaphragm 60, which is in contact with the upper level of ink ink supply may be described as resting thereon, follows the ink level as the ink is gradually withdrawn from chamber C. Such movement of diaphragm 60 continues until it reaches substantially the broken line position shown in FIG. 3. Sensing finger 80 (and sensing plate 72, when used) follow movement of diaphragm 60, to positions also indicated by the broken lines. In this position, sensing finger 80 causes the closing of switch 82 to restore power to motor M through circuit 84, thus actuating pump P to start the cycle to again fill chamber C with ink.

It is of particular importance to note that since diaphragm 60 is in contact with, and completely covers, the upper level of the ink during normal operation of the printing machine, there is no possibility of the surface of the ink in fountain 22 being subject to attack by oxygen as the diaphragm moves between its retracted and distended positions.

From the above explanation, it will readily be seen that movement of diaphragm 60 and sensing finger 80 between their retracted and distended positions control the starting and stopping of pump P to thereby maintain a substantially predetermined operating level of ink in fountain 22. This level is substantially greater than that maintained in the usual ink fountain, so that the possibility for leakage over the top of the fountain roller exists. This leakage, as explained above is prevented by the action of strip 86. The high level of ink in the fountain, moreover, provides a positive hydraulic head at the gap which is sealed by the strip 86, and thus discourages the introduction of the moistening fluid into the ink fountain by way of the surface of the fountain roller 20.

As mentioned hereinabove, it may be desirable under cer' tain conditions to provide a follower F, FIG. 4, to assist in the uniform withdrawal of ink from container 40. Such conditions may exist when stiff, pasty, or high-viscosity inks are employed. Normally, gravity beeps pump P primed. However, when the ink in the container is nearly exhausted, or at the approximate ink level shown in FIG. 4, gravity alone may not level the high-viscosity high-viscosity supply rapidly enough because of its stiff consistency. If this condition occurs, the pump pulls its ink from the center of the supply rapidly enough to form an air passage through to the surface. Pump P then sucks air and the ink flow stops well before container 40 is anywhere near empty. By using follower F, which it will be noted is of a dimension slightly less than the internal dimension of container 40, the suction created by pump P causes the ink body to move down uniformly and to prevent the formation of a central air passage so that practically all of the ink can be exhausted from container 40 by the pumping action.

When the ink supply is exhausted, i.e., the container 40 has been emptied (as indicated to the operator by a drop in pressure on gauge 54) it is a simple matter for the operator to remove the container 40 and discard it, replacing it with a new container 40 from which the tip 440 has been cut and whose cover 42 is then loosened. The whole operation can be performed in an instant with virtually no mess, and is required only at very infrequent intervals.

Because of the enclosed nature of the system, the ink can be allowed to stand in the machine indefinitely with no need ever to clean the fountain unless a change of ink color is desired.

While preferred embodiments of the invention have been described and illustrated, it is to be understood that these are capable of variation and modification. Accordingly, the aim in the appended claims is to cover all such variations and modifications as may fall within the true spirit of the invention.

We claim:

1. An enclosed ink supply system for a printing machine in which the ink is protected from exposure to the atmosphere, comprising:

an ink fountain mounted on the printing machine, said ink fountain having a pair of openings therein;

an ink fountain roller rotatably mounted in one of said openings in said ink fountain in air-excluding relationship therewith;

a flexible diaphragm associated with the ink fountain so as to close the other opening in the fountain to thereby provide a substantially enclosed ink fountain structure in which the ink in the fountain is in contact with the walls of the fountain, the roller and the diaphragm and air is excluded from the fountain interior, said diaphragm adapted to flex between a retracted position and a distended position in relation to said fountain;

a sensing finger coacting with the exterior of said diaphragm and movable thereby between said retracted and distended positions;

an air-excluding source of ink supply;

power means for feeding the ink from the supply source to the ink fountain; and

switching means controlled by the sensing finger for activating said power means when the diaphragm is in the retracted position to thereby supply ink from the supply source to the fountain, and for deactivating the power means to thereby discontinue the supplying of ink to the fountain when the diaphragm is in the distended position.

2. An ink system according to claim 1, in which a sensing plate rests freely on said diaphragm in interposition between said diaphragm and said sensing finger and is movable with the diaphragm between said retracted and distended positions.

3. An ink system according to claim 1, in which said power means comprises an intermittently driven pump having an inlet for receiving ink from said supply source and an outlet connected with said fountain.

4. An ink system according to claim 1, in which said supply source comprises a container which includes a follower to assist in uniform withdrawal of the ink from the container under the effects of atmospheric pressure.

5. An ink system according to claim I, in which an elongated fiexible strip extends from said ink fountain to a portion of the periphery of said ink fountain roller so as to form a seal therebetween.

6. An enclosed ink supply system for a printing machine in which the ink is protected from exposure to the atmosphere, comprising:

an ink fountain mounted on the printing machine, said ink fountain having a pair of openings therein;

an ink fountain roller rotatably mounted in one of said openings in said ink fountain in air-excluding relationship therewith;

a flexible diaphragm associated with the ink fountain so as thereto with a mating sealing fit, and ready disconnection therefrom, said container having the end opposite said neck closed by a removable cover to permit filling and allow air access during emptying;

to close the other opening in the fountain to thereby proan ink fountain mounted on the printing machine and convide a substantially enclosed ink fountain structure in nected to the pumping means by a passageway, said ink which the ink in the fountain is in contact with the walls fountain having a pair of openings therein; of the fountain, the roller and the diaphragm and air is exan ink f untain roller rotatably mounted in one of said eluded from the fountain interior, said diaphragm p ning in Said ink fountain; adapted to flex between a retracted position and 3 l0 means to seal any gap between the roller and the fountain; distended position in relation to aid fountain; a flexible diaphragm associated with the ink fountain so as a sensing finger coacting with the exterior of said diaphragm to close the other opening in the fountain to thereby proand movable thereby b t id a m d d vide a substantially enclosed ink fountain structure distended position whereby the surface of the ink is protected by the an air-excluding source fi k supply; diaphragm against possible oxidation, said diaphragm power means for feeding the ink from the supply source to adapted to flex between a retracted Position and a the ink fou t in; and distended position in relation to said fountain; switching means controlled by the sensing finger for activata Sensing finger sulmrimposfid 011 Said diaphragm and aing said power means when the diaphragm is in the ble therewlth between said retracted and distended poslretracted position to thereby supply ink from the supply hohs; source to the fountain, and for deactivating the power means to achvate sald P p means for feeding {he i means to thereby discontinue the supplying of ink to the from h Cohmmel' through the passageway to the fountain when the diaphragm is in the distended position, f h and h retracted position f the diaphragm being at a level sw tching means controlled by the sensing finger for activatsuch that the ink in said fountain will be well above the mg 531d Power meahs when the diaphragm 15 m the top of the fountain roller to thereby maintain a significant head of ink pressure to discourage moisture entrained by the fountain roller from entering the fountain.

7. An enclosed ink supply system for a printing machine retracted position to thereby supply ink from the container to the fountain, and for arresting the power means to thereby discontinue the supplying of ink to the fountain when the diaphragm is in the distended position.

8. An enclosed ink supply system as set forth in claim 7 in which said container includes a follower to assist in uniform withdrawal of the ink from the container.

comprising:

pumping means including an inlet fitting:

a container filled with printing ink, said container having a neck compatible with said fitting for ready connection 

1. An enclosed ink supply system for a printing machine in which the ink is protected from exposure to the atmosphere, comprising: an ink fountain mounted on the printing machine, said ink fountain having a pair of openings therein; an ink fountain roller rotatably mounted in one of said openings in said ink fountain in air-excluding relationship therewith; a flexible diaphragm associated with the ink fountain so as to close the other opening in the fountain to thereby provide a substantially enclosed ink fountain structure in which the ink in the fountain is in contact with the walls of the fountain, the roller and the diaphragm and air is excluded from the fountain interior, said diaphragm adapted to flex between a retracted position and a distended position in relation to said fountain; a sensing finger coacting with the exterior of said diaphragm and movable thereby between said retracted and distended positions; an air-excluding source of ink supply; power means for feeding the ink from the supply source to the ink fountain; and switching means controlled by the sensing finger for activating said power means when the diaphragm is in the retracted position to thereby supply ink from the supply source to the fountain, and for deactivating the power means to thereby discontinue the supplying of ink to the fountain when the diaphragm is in the distended position.
 2. An ink system according to claim 1, in which a sensing plate rests freely on said diaphragm in interposition between said diaphragm and said sensing finger and is movable with the diaphragm between said retracted and distended positions.
 3. An ink system according to claim 1, in which said power means comprises an intermittently driven pump having an inlet for receiving ink from said supply source and an outlet connected with said fountain.
 4. An ink system according to claim 1, in which said supply source comprises a container which includes a follower to assist in uniform withdrawal of the ink from the container under the effects of atmospheric pressure.
 5. An ink system according to claim 1, in which an elongated flexible strip extends from said ink fountain to a portion of the periphery of said ink fountain roller so as to form a seal therebetween.
 6. An enclosed ink supply system for a printing machine in which the ink is protected from exposure to the atmosphere, comprising: an ink fountain mounted on the printing machine, said ink fountain having a pair of openings therein; an ink fountain roller rotatably mounted in one of said openings in said ink fountain in air-excluding relationship therewith; a flexible diaphragm associated with the ink fountain so as to close the other opening in the fountain to thereby provide a substantially enclosed ink fountain structure in which the ink in the fountain is in contact with the walls of the fountain, the roller and the diaphragm and air is excluded from the fountain interior, said diaphragm adapted to flex between a retracted position and a distended position in relation to said fountain; a sensing finger coacting with the exterior of said diaphragm and movable thereby between said retracted and distended positions; an air-excluding source of ink supply; power means for feeding the ink from the supply source to the ink fountain; and switching means controlled by the sensing finger for activating said power means when the diaphragm is in the retracted position to thereby supply ink from the supply source to the fountain, and for deactivating the power means to thereby discontinue the supplying of ink to the fountain when The diaphragm is in the distended position, the retracted position of the diaphragm being at a level such that the ink in said fountain will be well above the top of the fountain roller to thereby maintain a significant head of ink pressure to discourage moisture entrained by the fountain roller from entering the fountain.
 7. An enclosed ink supply system for a printing machine, comprising: pumping means including an inlet fitting; a container filled with printing ink, said container having a neck compatible with said fitting for ready connection thereto with a mating sealing fit, and ready disconnection therefrom, said container having the end opposite said neck closed by a removable cover to permit filling and allow air access during emptying; an ink fountain mounted on the printing machine and connected to the pumping means by a passageway, said ink fountain having a pair of openings therein; an ink fountain roller rotatably mounted in one of said openings in said ink fountain; means to seal any gap between the roller and the fountain; a flexible diaphragm associated with the ink fountain so as to close the other opening in the fountain to thereby provide a substantially enclosed ink fountain structure whereby the surface of the ink is protected by the diaphragm against possible oxidation, said diaphragm adapted to flex between a retracted position and a distended position in relation to said fountain; a sensing finger superimposed on said diaphragm and movable therewith between said retracted and distended positions; means to activate said pumping means for feeding the ink from the container through the passageway to the ink fountain; and switching means controlled by the sensing finger for activating said power means when the diaphragm is in the retracted position to thereby supply ink from the container to the fountain, and for arresting the power means to thereby discontinue the supplying of ink to the fountain when the diaphragm is in the distended position.
 8. An enclosed ink supply system as set forth in claim 7 in which said container includes a follower to assist in uniform withdrawal of the ink from the container. 